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Mack C, Gibson JS, Meler E, Woldeyohannes S, Yuen N, Herndon A. Antimicrobial susceptibility patterns of aerobic bacteria isolated from canine urinary samples in South East Queensland, 2013 to 2018. Aust Vet J 2024. [PMID: 38654674 DOI: 10.1111/avj.13333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 03/10/2024] [Accepted: 04/01/2024] [Indexed: 04/26/2024]
Abstract
Urinary tract infections are a common diagnosis in dogs presenting to veterinary practice. Veterinarians often treat suspected infections empirically, either in the absence of culture and susceptibility testing results or whilst waiting for them. This study aimed to identify the bacteria most frequently isolated from canine urinary samples and their antimicrobial susceptibility patterns in South East Queensland (SEQ) to help guide responsible empirical antimicrobial prescription by the veterinary community in this geographical location. Cumulative antibiograms were generated from the results of 1284 culture-positive urinary samples in SEQ, obtained from a commercial veterinary laboratory over a 5-year period. Escherichia coli was the most commonly isolated bacterial species (43%), followed by Staphylococcus spp. (23%), Proteus spp. (21%) and Enterococcus spp. (10%). Of the six most common isolates, 97% had susceptibility to at least one low-importance antimicrobial. Susceptibility to the low-importance and first-line antimicrobial recommendation, amoxicillin, was 81% for E. coli and 24% for Staphylococcus spp. Susceptibility of both E. coli and Staphylococcus spp. to medium-importance and commonly recommended empirical antimicrobials, trimethoprim sulphonamides and amoxicillin-clavulanic acid was ≥85% and >92% for high-importance antimicrobials enrofloxacin and ceftiofur. Of the E. coli and Staphylococcus spp. isolates, 8.8% and 4%, respectively, were considered multidrug resistant. There was no increase in resistance to antimicrobials detected over the study period. Susceptibilities suggest low- and medium-importance antimicrobials remain acceptable first-line empirical treatments. However, this should be continually assessed and updated using local surveillance data.
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Affiliation(s)
- C Mack
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - J S Gibson
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - E Meler
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - S Woldeyohannes
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - N Yuen
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - A Herndon
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
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Langhorne C, Wood BJ, Wood C, Henning J, McGowan M, Schull D, Ranjbar S, Gibson JS. Understanding barriers to reducing antimicrobials on Australian dairy farms: A qualitative analysis. Aust Vet J 2024. [PMID: 38342502 DOI: 10.1111/avj.13322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 01/21/2024] [Indexed: 02/13/2024]
Abstract
INTRODUCTION Reducing antibiotic use in production animal systems is one strategy which may help to limit the development of antimicrobial resistance. To reduce antimicrobial use in food-producing animals, it is important to first understand how antibiotics are used on farm and what barriers exist to decreasing their use. In dairy production systems, mastitis is one of the most common reasons for administering antimicrobials. Therefore, it is important to understand the motivations and behaviours of dairy farmers in relation to the diagnosis, treatment and prevention of mastitis. MATERIALS AND METHODS In this study, we interviewed a sample of dairy farmers and dairy industry professionals from the major dairying regions of eastern Australia regarding their current practices used to diagnose, treat, and control subclinical and clinical mastitis. Inductive thematic analysis was used to code interview transcripts and identify the recurrent themes. RESULTS Four overarching themes were identified: (1) the challenges associated with the detection and diagnosis of clinical mastitis, including with laboratory culture, (2) the motivations behind treatment decisions for different cases, (3) decisions around dry cow therapy and the role of herd recording, and (4) concerns regarding the development of antimicrobial resistance. DISCUSSION This study identifies several challenges which may limit the ability of Australian dairy farmers to reduce antimicrobial use on farm, such as the need for rapid and reliable diagnostic tests capable of identifying the pathogenic causes of mastitis and the difficulties associated with conducting herd recording for the implementation of selective dry cow therapy. Industry professionals were concerned that farmers were not using individual cow records to aid in treatment decisions, which could result in unnecessary antimicrobial use. The results of this study can act as the basis for future research aimed at assessing these issues across the broader Australian dairy industry.
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Affiliation(s)
- C Langhorne
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - B J Wood
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - C Wood
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - J Henning
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - M McGowan
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - D Schull
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - S Ranjbar
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - J S Gibson
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
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Awawdeh L, Turni C, Mollinger JL, Henning J, Cobbold RN, Trott DJ, Gibson JS. Antimicrobial susceptibility, plasmid replicon typing, phylogenetic grouping, and virulence potential of avian pathogenic and faecal Escherichia coli isolated from meat chickens in Australia. Avian Pathol 2022; 51:349-360. [PMID: 35417283 DOI: 10.1080/03079457.2022.2065969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Globally, avian colibacillosis is a leading cause of morbidity and mortality in poultry, associated with economic losses and welfare problems. Here, clinical avian pathogenic E. coli isolates (CEC; n=50) and faecal E. coli isolates from healthy (FEC; n=187) Australian meat chickens collected between 2006 and 2014 were subjected to antimicrobial susceptibility testing, phylogenetic grouping, plasmid replicon (PR) typing, multilocus sequence typing, and virulence gene (VG) profiling. Extended-spectrum cephalosporin (ESC)- and fluoroquinolone (FQ)-resistant E. coli isolates underwent further genetic characterisation. Significant proportions of CEC and FEC were respectively susceptible (13/50 [26%]; 48/187 [26%],) or MDR (9/50 [18%]; 26/187 [14%]) to 20 tested antimicrobials. Phylogenetic groups A and C, and PR types IncFIB and IncFrep were most commonly represented. Five tested CEC-associated VGs were more prevalent in CEC (≥90%) compared to FEC isolates (≤58%). Some isolates (CEC n=3; FEC n=7) were resistant to ESCs and/or FQs and possessed signature mutations in chromosomal FQ target genes and plasmid-mediated qnrS, blaCMY-2, and blaDHA-1 genes. Sequence type 354 (n=4), associated with extraintestinal infections in a broad range of hosts, was prevalent among the ESC- and/or FQ-resistant FEC.This study confirmed the existence of a small reservoir of ESC- and FQ-resistant E. coli in Australian commercial meat chickens despite the absence of use in the industry of these drug classes. Otherwise, a diversity of VGs and PR types in both faecal and clinical E. coli populations were identified. It's hypothesised that the source of ESC- and FQ-resistant E. coli may be external to poultry production facilities.Highlights1. Low-level resistance to older and newer generation antimicrobial drugs detected2. The most common sequence type (ST) associated with FQ resistance was ST354 (4/10)3. A small proportion of CEC (n=3) and FEC (n=7) were resistant to ESCs and/or FQs.
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Affiliation(s)
- L Awawdeh
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia.,Eastern Institute of Technology, Hawke's Bay, 501 Gloucester Street, Taradale, Napier 4112, New Zealand
| | - C Turni
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Dutton Park, Queensland 4102, Austalia
| | - J L Mollinger
- Department of Agriculture and Fisheries, Health & Food Science Precinct, Coopers Plains, Queensland 4108, Australia
| | - J Henning
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
| | - R N Cobbold
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
| | - D J Trott
- Australian Centre for Antimicrobial Resistance Ecology, The University of Adelaide, Roseworthy Campus, Mudla Wirra Rd, Roseworthy, 5371, Australia
| | - J S Gibson
- School of Veterinary Science, The University of Queensland, Gatton, Queensland 4343, Australia
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Fletcher JR, Yuen KY, Stewart AJ, Young AC, Gibson JS, James OA, Medina-Torres CE, Forde BM, Sole-Guitart A. Successful treatment of a chronic oroantral fistula infected with extensively drug resistant bacteria using long-term oesophageal tube feeding and several non-conventional treatments in a horse. Aust Vet J 2021; 100:107-113. [PMID: 34859426 DOI: 10.1111/avj.13136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 08/21/2021] [Accepted: 11/11/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Chronic oroantral fistulae (OAF) with secondary sinusitis can occur following repulsion of cheek teeth in horses. CASE REPORT An 8-year-old Andalusian cross gelding presented with an iatrogenic clinical crown fracture of tooth 209, which underwent repulsion of its apical portion (day 0). The horse was treated with intramuscular penicillin and intravenous gentamicin (5 days), followed by oral trimethoprim-sulphonamide (10 days) and then oral doxycycline (14 days). The acute iatrogenic OAF created during the initial repulsion persisted; a chronic OAF was identified on day 24. On day 48, septic sinusitis with multidrug-resistant (MDR) Escherichia coli was confirmed. Although susceptible to enrofloxacin in vitro, 30 days of therapy was unsuccessful. Subsequent serial cultures grew multiple MDR and extensively drug-resistant (XDR) gram-negative microorganisms. Whole-genome sequencing (WGS) revealed multiple sequence types of E. coli, with a range of resistance and virulence genes. The orientation of the OAF, regional osteomyelitis and septic sinusitis were confirmed with computed tomography on day 70. On day 74, enteral nutrition was provided through a cervical oesophagostomy tube for 3 months for prevention of oral feed contamination. The OAF was treated with various alternative therapeutics, including apple cider vinegar, propolis and amikacin impregnated products, until resolution on day 116. CONCLUSION These non-conventional therapeutics, antimicrobials and long-term oesophagostomy contributed to the successful treatment of a complicated OAF. In the future, WGS may be useful to inform antimicrobial selection when MDR or XDR organisms are identified.
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Affiliation(s)
- J R Fletcher
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - K Y Yuen
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - A J Stewart
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - A C Young
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - J S Gibson
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - O A James
- Australian Veterinary Equine Dentistry, Clayfield, Queensland, 4011, Australia
| | - C E Medina-Torres
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - B M Forde
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland, 4072, Australia
| | - A Sole-Guitart
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
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Kalnins NJ, Haworth M, Croton C, Gibson JS, Stewart AJ, Purcell SL. Treatment of moderate grade dog bite wounds using amoxicillin-clavulanic acid with and without enrofloxacin: a randomised non-inferiority trial. Aust Vet J 2021; 99:369-377. [PMID: 34151420 DOI: 10.1111/avj.13093] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/23/2021] [Accepted: 05/08/2021] [Indexed: 12/19/2022]
Abstract
BACKGROUND Dog-to-dog bite wounds are a common veterinary emergency presentation: despite this, there is insufficient information to guide veterinarians on appropriate empirical antimicrobial management. OBJECTIVES Investigate the effectiveness of amoxicillin-clavulanic acid with and without enrofloxacin in the treatment of moderate grade dog bite wounds (DBW). To describe common pathogens and their antimicrobial susceptibility patterns. MATERIALS AND METHODS In a single-centre parallel group pragmatic trial, 50 dogs presenting with moderate grade DBW were prospectively randomised to receive amoxicillin-clavulanic acid (group A) or amoxicillin-clavulanic acid and enrofloxacin (group B). Swabs were taken for culture and susceptibility testing at admission. Stabilisation, wound care and surgical debridement were performed at the discretion of admitting clinicians. The primary outcome was complication due to infection at 10 days, with Bayesian inference used to estimate the difference in proportions between treatment groups. RESULTS Of the 24 dogs in treatment group A, 1 required the addition of enrofloxacin at re-examination. None of the 26 dogs in group B required alteration of antimicrobial coverage. The difference in complication rate due to infection between treatment groups was 4.2%. Twenty-one different organisms were identified: Staphylococcus pseudintermedius, Neisseria spp., Pasteurella multocida and P. canis were the most common. Over 90% of gram-negative and gram-positive isolates were susceptible to amoxicillin-clavulanic acid. Ninety-six percent of gram-negative and 86% of gram-positive isolates were susceptible to enrofloxacin. CONCLUSION AND CLINICAL SIGNIFICANCE Amoxicillin-clavulanic acid is an appropriate empirical antimicrobial choice for moderate DBW in South East Queensland. Reduced empirical enrofloxacin use will promote antimicrobial stewardship and potentially antimicrobial resistance.
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Affiliation(s)
- N J Kalnins
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - M Haworth
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - C Croton
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
- Faculty of Health, Engineering and Sciences, School of Sciences, University of Southern Queensland, Toowoomba, Queensland, Australia
| | - J S Gibson
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - A J Stewart
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - S L Purcell
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
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Wood CM, Perkins NR, Tozer SJ, Johnson W, Barnes TS, McGowan M, Gibson JS, Alawneh J, Firestone SM, Woldeyohannes SM. Prevalence and spatial distribution of Coxiella burnetii seropositivity in northern Australian beef cattle adjusted for diagnostic test uncertainty. Prev Vet Med 2021; 189:105282. [PMID: 33556799 DOI: 10.1016/j.prevetmed.2021.105282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 01/14/2021] [Accepted: 01/20/2021] [Indexed: 11/24/2022]
Abstract
Q fever is a zoonotic disease caused by infection with Coxiella burnetii transmitted from animals including, but not limited to, cattle, sheep and goats. The infection in cattle is typically sub-clinical with some evidence suggesting associated reproductive loss. There is currently limited data on the true prevalence and distribution of coxiellosis in beef cattle across northern Australia. During this study, 2,012 sera samples from beef cattle managed on commercial farms located in Queensland and the Northern Territory were tested using an indirect immunofluorescent assay (IFA) for serological evidence of IgG antibodies against C. burnetii. Bayesian latent class models were used to estimate the true prevalence, adjusted for diagnostic test sensitivity and specificity and incorporating the hierarchical structure of the cattle within farms and regions. In this study, cattle in the Northern Territory had lower estimated true prevalence than cattle within most regions of Queensland with the exception of south-east Queensland. Results from this study have described the geographic distribution and estimated the true prevalence of antibodies to C. burnetii in a sample of extensively managed beef cattle located across the tropical grazing regions of northern Australia.
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Affiliation(s)
- C M Wood
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia; Centre for Children's Health Research, Queensland Paediatric Infectious Disease Laboratory, Lady Cilento Research Precinct, South Brisbane, Queensland, 4101, Australia.
| | - N R Perkins
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
| | - S J Tozer
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia; Centre for Children's Health Research, Queensland Paediatric Infectious Disease Laboratory, Lady Cilento Research Precinct, South Brisbane, Queensland, 4101, Australia
| | - W Johnson
- The University of California, Irvine, Department of Statistics, Irvine, CA, 92617, United States
| | - T S Barnes
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia; The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, Gatton, Queensland, 4343, Australia
| | - M McGowan
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
| | - J S Gibson
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
| | - J Alawneh
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
| | - S M Firestone
- The University of Melbourne, Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, Parkville, Victoria, 3010, Australia
| | - S M Woldeyohannes
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
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Gibson JS, Blackall PJ. OBITUARIES
Michael Desmond Connole 1927 – 2020. Aust Vet J 2021. [DOI: 10.1111/avj.13054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wadud R, Hannemann A, Rees DC, Brewin JN, Gibson JS. Yoda1 and phosphatidylserine exposure in red cells from patients with sickle cell anaemia. Sci Rep 2020; 10:20110. [PMID: 33208899 PMCID: PMC7674503 DOI: 10.1038/s41598-020-76979-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/01/2020] [Indexed: 01/27/2023] Open
Abstract
Phosphatidylserine (PS) exposure is increased in red cells from sickle cell anaemia (SCA) patients. Externalised PS is prothrombotic and attractive to phagocytes and activated endothelial cells and thus contributes to the anaemic and ischaemic complications of SCA. The mechanism of PS exposure remains uncertain but it can follow increased intracellular Ca2+ concentration ([Ca2+]i). Normally, [Ca2+]i is maintained at very low levels but in sickle cells, Ca2+ permeability is increased, especially following deoxygenation and sickling, mediated by a pathway sometimes called Psickle. The molecular identity of Psickle is also unclear but recent work has implicated the mechanosensitive channel, PIEZO1. We used Yoda1, an PIEZO1 agonist, to investigate its role in sickle cells. Yoda1 caused an increase in [Ca2+]i and PS exposure, which was inhibited by its antagonist Dooku1 and the PIEZO1 inhibitor GsMTx4, consistent with functional PIEZO1. However, PS exposure did not necessitate an increase in [Ca2+]i. Two PKC inhibitors were also tested, chelerytherine chloride and calphostin C. Both reduced PS exposure whilst chelerytherine chloride also reduced Yoda1-induced increases in [Ca2+]i. Findings are therefore consistent with the presence of PIEZO1 in sickle cells, able to mediate Ca2+ entry but that PKC was also involved in both Ca2+ entry and PS exposure.
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Affiliation(s)
- R Wadud
- Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK
| | - A Hannemann
- Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK
| | - D C Rees
- Department of Paediatric Haematology, King's College Hospital, Denmark Hill, London, SE5 5RL, UK
| | - J N Brewin
- Department of Paediatric Haematology, King's College Hospital, Denmark Hill, London, SE5 5RL, UK
| | - J S Gibson
- Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK.
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Fellows AP, Casford MTL, Davies PB, Gibson JS, Brewin JN, Rees DC. Nanoscale adhesion profiling and membrane characterisation in sickle cell disease using hybrid atomic force microscopy-IR spectroscopy. Colloids Surf B Biointerfaces 2020; 197:111383. [PMID: 33039752 DOI: 10.1016/j.colsurfb.2020.111383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/13/2020] [Accepted: 09/24/2020] [Indexed: 10/23/2022]
Abstract
Sickle cell disease (SCD) presents a significant global health problem. At present there is no effective treatment, with most being supportive for its associated complications such as the vaso-occlusive crises that result from increased cell adhesion. Hypoxic sickle cells have previously shown greater phosphatidylserine (PS) exposure and oxidative damage, as well as being notably "stickier" suggesting that increased cell cohesion and adhesion to the blood vessel endothelium is a possible mechanism for vaso-occlusion. The present work uses the hybrid technique of atomic force microscopy nano-infrared spectroscopy (AFM-IR) to probe changes to the coefficient of friction and C-O IR intensity in SCD on a nanoscale for dried red blood cells (RBCs) fixed under conditions of hypoxia and correlates these observations with adhesive interactions at the membrane. Using functionalised AFM tips, it has been possible to probe adhesive interactions between hydrophilic and hydrophobic moieties exposed at the surface of the dried RBCs fixed under different oxygenation states and for different cell genotypes. The results are consistent with greater PS-exposure and oxidative damage in hypoxic sickle cells, as previously proposed, and also show strong correlation between localised oxidative damage and increased adhesion. A mechanistic explanation involving significant lipid tail disruption as a result of oxidative action, in combination with differing concentrations of externalised PS lipids, is proposed to explain the observed adhesion behaviour of each type of cell.
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Affiliation(s)
- A P Fellows
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - M T L Casford
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - P B Davies
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
| | - J S Gibson
- Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK.
| | - J N Brewin
- Department of Paediatric Haematology, King's College Hospital, London, SE5 9RS, UK
| | - D C Rees
- Department of Paediatric Haematology, King's College Hospital, London, SE5 9RS, UK
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Norris JM, Heller J, Gibson JS, Hardefeldt LY, Hyndman TH, Nielsen TD, Ward MP, Govendir M, Chambers JP, Browning GF, Wingett K, Britton S. Development of a veterinary antimicrobial stewardship online training program for Australian veterinarians: a national collaborative effort. Aust Vet J 2019; 97:290-291. [PMID: 31286468 DOI: 10.1111/avj.12821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 02/18/2019] [Indexed: 11/29/2022]
Affiliation(s)
- J M Norris
- Sydney School of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia
| | - J Heller
- School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia
| | - J S Gibson
- School of Veterinary Science, University of Queensland, Gatton, Queensland, Australia
| | - L Y Hardefeldt
- Melbourne Veterinary School, University of Melbourne, Parkville, and National Centre for Antimicrobial Stewardship, Peter Doherty Institute, Carlton, Victoria, Australia
| | - T H Hyndman
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia
| | - T D Nielsen
- University of Adelaide School of Animal and Veterinary Science, Adelaide, South Australia, Australia
| | - M P Ward
- Sydney School of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia
| | - M Govendir
- Sydney School of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia
| | - J P Chambers
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - G F Browning
- Melbourne Veterinary School, University of Melbourne, Parkville, and National Centre for Antimicrobial Stewardship, Peter Doherty Institute, Carlton, Victoria, Australia
| | - K Wingett
- NSW Department of Primary Industries Biosecurity and Food Safety, Orange, New South Wales, Australia
| | - S Britton
- Department of Industry Skills and Regional Development, NSW Department of Primary Industries, Orange, New South Wales, Australia
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Smith MG, Jordan D, Gibson JS, Cobbold RN, Chapman TA, Abraham S, Trott DJ. Phenotypic and genotypic profiling of antimicrobial resistance in enteric Escherichia coli communities isolated from finisher pigs in Australia. Aust Vet J 2018; 94:371-6. [PMID: 27671081 DOI: 10.1111/avj.12491] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/23/2015] [Accepted: 12/11/2015] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To assess herd-to-herd variation in antimicrobial resistance phenotypes and associated antimicrobial resistance genes (ARGs) in faecal commensal Escherichia coli communities isolated from Australian slaughter-age pigs. METHODS Hydrophobic grid-membrane filtration (HGMF) was used to screen populations of E. coli isolated from faecal samples obtained from pigs prior to or at slaughter. Multiplex PCRs were applied to the pooled DNA extracted from the samples to identify specific ARGs. METHODS Pooled faecal samples from 30 finishers, from 72 different Australian pig farms, produced 5003 isolates for screening. HGMF techniques and image analysis were used to confirm E. coli resistance phenotypes to four antimicrobial agents (ampicillin, gentamicin, florfenicol and ceftiofur) using selective agars. Multiplex PCRs were performed on DNA from pooled samples for 35 ARGs associated with seven chemical classes. RESULTS The prevalence of E. coli isolates showing no resistance to any of the drugs was 50.2% (95% confidence interval (CI) 41.8-58.6%). Ceftiofur resistance was very low (1.8%; CI 0.8-3.9%) and no ARGs associated with 3rd-generation cephalosporin resistance were detected. By contrast, ampicillin (29.4%, CI 22.8-37.0%), florfenicol (24.3%, CI 17.8-32.3%) and gentamicin (CI 17.5%, 10.7-27.2%) resistance prevalence varied greatly between farms and associated ARGs were common. The most common combined resistance phenotype was ampicillin-florfenicol. CONCLUSION The use of registered antimicrobials in Australian pigs leads to the enteric commensal populations acquiring associated ARGs. However, despite a high intensity of sampling, ARGs imparting resistance to the critically important 3rd-generation cephalosporins were not detected.
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Affiliation(s)
- M G Smith
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
| | - D Jordan
- New South Wales Department of Primary Industries, Wollongbar, NSW, Australia
| | - J S Gibson
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia.
| | - R N Cobbold
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
| | - T A Chapman
- Elizabeth MacArthur Agricultural Institute, New South Wales Department of Primary Industries, Menangle, NSW, Australia
| | - S Abraham
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA, Australia.,School of Veterinary and Life Sciences, Murdoch University, WA, Australia
| | - D J Trott
- School of Animal and Veterinary Sciences, The University of Adelaide, Roseworthy, SA, Australia
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Dayao DAE, Gibson JS, Blackall PJ, Turni C. Antimicrobial resistance genes inActinobacillus pleuropneumoniae,Haemophilus parasuisandPasteurella multocidaisolated from Australian pigs. Aust Vet J 2016; 94:227-31. [DOI: 10.1111/avj.12458] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 09/09/2015] [Accepted: 10/28/2015] [Indexed: 01/04/2023]
Affiliation(s)
- DAE Dayao
- The University of Queensland; School of Veterinary Science; Gatton Queensland 4343 Australia
| | - JS Gibson
- The University of Queensland; School of Veterinary Science; Gatton Queensland 4343 Australia
| | - PJ Blackall
- The University of Queensland; Queensland Alliance for Agriculture and Food Innovation; EcoSciences Precinct QLD Australia
| | - C Turni
- The University of Queensland; Queensland Alliance for Agriculture and Food Innovation; EcoSciences Precinct QLD Australia
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13
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Owen H, Buckle K, Olm J, Leitner M, Pandey S, Gaughan JB, Sullivan ML, Lees AM, Gibson JS. Isolation of Nocardia mexicana from focal proliferative tenosynovitis and arthritis in a steer. Aust Vet J 2016; 93:170-3. [PMID: 25939264 DOI: 10.1111/avj.12308] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 06/14/2014] [Accepted: 08/31/2014] [Indexed: 11/29/2022]
Abstract
CASE REPORT An 18-month-old Charolais steer was presented with lameness and fluctuant swelling of the right stifle joint, which yielded neutrophils on fine-needle aspiration. A diagnosis of bacterial proliferative tenosynovitis and arthritis was made on postmortem and histological examination. Culture and 16S rRNA sequencing identified a Nocardia sp. with 99% homology with the corresponding DNA fragment of N. mexicana DSM 44952. Antimicrobial susceptibility testing revealed the isolate was susceptible to co-trimoxazole and third-generation cephalosporins. CONCLUSION We report the first case, both in Australia and internationally, of proliferative tenosynovitis and arthritis caused by Nocardia spp. infection in a bovine and the first report of pathology attributed to N. mexicana in a veterinary patient. Given the limited susceptibility of the bacteria, the poor antimicrobial penetration that would be expected and the morphological changes that had taken place in the joint; the steer would have required protracted antimicrobial treatment in addition to invasive debridement of the lesion. This case emphasises the importance of routinely performing cytology and extended incubation of cultures in cases of arthritis in order to make ethical and economically viable treatment decisions.
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Affiliation(s)
- H Owen
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, 4343, Australia
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14
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Hannemann A, Cytlak UMC, Gbotosho OT, Rees DC, Tewari S, Gibson JS. Effects of o-vanillin on K⁺ transport of red blood cells from patients with sickle cell disease. Blood Cells Mol Dis 2014; 53:21-6. [PMID: 24594314 PMCID: PMC4039999 DOI: 10.1016/j.bcmd.2014.02.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 01/24/2014] [Indexed: 01/26/2023]
Abstract
Aromatic aldehydes like o-vanillin were designed to reduce the complications of sickle cell disease (SCD) by interaction with HbS, to reduce polymerisation and RBC sickling. Present results show that o-vanillin also directly affects RBC membrane permeability. Both the K(+)-Cl(-) cotransporter (KCC) and the Ca(2+)-activated K(+) channel (or Gardos channel) were inhibited with IC50 of about 0.3 and 1 mM, respectively, with activities almost completely abolished by 5 mM. Similar effects were observed in RBCs treated with the thiol reacting reagent N-ethylmaleimide or with the Ca(2+) ionophore A23187, to circumvent any action via HbS polymerisation. The deoxygenation-induced cation conductance (sometimes termed P(sickle)) was partially inhibited, whilst deoxygenation-induced exposure of phosphatidylserine was completely abrogated. Na(+)/K(+) pump activity was also reduced. Notwithstanding, o-vanillin stimulated K(+) efflux through an unidentified pathway and resulted in reduction in cell volume (as measured by wet weight-dry weight). These actions are relevant to understanding how aromatic aldehydes may affect RBC membrane permeability per se as well as HbS polymerisation and thereby inform design of compounds most efficacious in ameliorating the complications of SCD.
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Affiliation(s)
- A Hannemann
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, United Kingdom
| | - U M C Cytlak
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, United Kingdom
| | - O T Gbotosho
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, United Kingdom
| | - D C Rees
- Department of Paediatric Haematology, King's College London School of Medicine, King's College Hospital NHS Foundation Trust, Denmark Hill, London, SE5 9RS, United Kingdom
| | - S Tewari
- Department of Paediatric Haematology, King's College London School of Medicine, King's College Hospital NHS Foundation Trust, Denmark Hill, London, SE5 9RS, United Kingdom
| | - J S Gibson
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, United Kingdom.
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15
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Horwood PF, Schibrowski ML, Fowler EV, Gibson JS, Barnes TS, Mahony TJ. IsMycoplasma bovisa missing component of the bovine respiratory disease complex in Australia? Aust Vet J 2014; 92:185-91. [DOI: 10.1111/avj.12184] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2013] [Indexed: 12/14/2022]
Affiliation(s)
- PF Horwood
- Animal Science; Queensland Department of Agriculture, Fisheries & Forestry; St Lucia Queensland Australia
| | - ML Schibrowski
- The University of Queensland; School of Veterinary Science; Gatton Queensland Australia
- The University of Queensland; Queensland Alliance for Agriculture and Food Innovation; Centre for Animal Science; St Lucia Queensland 4072 Australia
| | - EV Fowler
- Animal Science; Queensland Department of Agriculture, Fisheries & Forestry; St Lucia Queensland Australia
| | - JS Gibson
- The University of Queensland; School of Veterinary Science; Gatton Queensland Australia
| | - TS Barnes
- The University of Queensland; Queensland Alliance for Agriculture and Food Innovation; Centre for Animal Science; St Lucia Queensland 4072 Australia
| | - TJ Mahony
- The University of Queensland; Queensland Alliance for Agriculture and Food Innovation; Centre for Animal Science; St Lucia Queensland 4072 Australia
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16
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Smith M, Do TN, Gibson JS, Jordan D, Cobbold RN, Trott DJ. Comparison of antimicrobial resistance phenotypes and genotypes in enterotoxigenic Escherichia coli isolated from Australian and Vietnamese pigs. J Glob Antimicrob Resist 2014; 2:162-167. [PMID: 27873723 DOI: 10.1016/j.jgar.2014.03.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/18/2014] [Accepted: 03/31/2014] [Indexed: 10/25/2022] Open
Abstract
This study aimed to compare the antibiogram phenotype and carriage of antimicrobial resistance genes (ARGs) of 97 porcine multidrug-resistant (MDR) enterotoxigenic Escherichia coli (ETEC) isolates obtained from Vietnam and 117 porcine MDR-ETEC obtained from Australia, two countries with different antimicrobial regulation systems. An antimicrobial resistance index (ARI) was calculated to quantify their potential significance to public health. Both Vietnamese and Australian isolates had moderate to high levels of resistance to commonly used antibiotics (ampicillin, tetracycline and sulphonamides). None of the Australian isolates were resistant to fluoroquinolones or third-generation cephalosporins and none possessed associated plasmid-mediated ARGs. However, 23.1% of Australian isolates were resistant to gentamicin owing to ARGs associated with apramycin or neomycin resistance [e.g. aac(3)-IV] that impart cross-resistance to gentamicin. Whilst Vietnamese isolates carried aminoglycoside ARGs, 44.4% of commercial pig isolates were resistant to gentamicin in comparison with 0% of village pig isolates. The plasmid-mediated fluoroquinolone ARG qnrB was commonly detected in Vietnamese isolates (52.3% commercial, 44.1% village), but phenotypic resistance was low (3.2% and 11.8%, respectively). The mean ARI for Vietnamese isolates (26.0) was significantly different (P<0.001) from the mean ARI for Australian isolates (19.8), primarily reflecting fluoroquinolone resistance in the former collection. This comparison suggests the effectiveness of regulations that slow the dissemination of 'critical' resistance by restricting the availability of important classes of antimicrobials.
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Affiliation(s)
- M Smith
- The University of Queensland, School of Veterinary Science, Gatton, QLD 4343, Australia
| | - T N Do
- National Institute of Veterinary Research (NIVR), 86 Truong Chinh, Hanoi, Vietnam
| | - J S Gibson
- The University of Queensland, School of Veterinary Science, Gatton, QLD 4343, Australia.
| | - D Jordan
- New South Wales Department of Primary Industries, Wollongbar, NSW 2477, Australia
| | - R N Cobbold
- The University of Queensland, School of Veterinary Science, Gatton, QLD 4343, Australia
| | - D J Trott
- School of Animal and Veterinary Sciences, The University of Adelaide, Mudla Wirra Road, Roseworthy, SA 5371, Australia
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17
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Cytlak UM, Hannemann A, Rees DC, Gibson JS. Identification of the Ca²⁺ entry pathway involved in deoxygenation-induced phosphatidylserine exposure in red blood cells from patients with sickle cell disease. Pflugers Arch 2013; 465:1651-60. [PMID: 23775402 PMCID: PMC3825215 DOI: 10.1007/s00424-013-1308-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 06/05/2013] [Accepted: 06/05/2013] [Indexed: 12/11/2022]
Abstract
Phosphatidylserine (PS) exposure in red blood cells (RBCs) from sickle cell disease (SCD) patients is increased compared to levels in normal individuals and may participate in the anaemic and ischaemic complications of SCD. Exposure is increased by deoxygenation and occurs with elevation of intracellular Ca2+ to low micromolar levels. The Ca2+ entry step has not been defined but a role for the deoxygenation-induced pathway, Psickle, is postulated. Partial Psickle inhibitors 4-acetamido-4′-isothiocyanostilbene-2,2′-disulphonic acid (SITS), 4,4′-dithiocyano-2,2′-stilbene-disulphonic acid (DIDS) and dipyridamole inhibited deoxygenation-induced PS exposure (DIDS IC50, 118 nM). Inhibitors and activators of other pathways (including these stimulated by depolarisation, benzodiazepines, glutamate and stretch) were without effect. Zn2+ and Gd3+ stimulated PS exposure to high levels. In the case of Zn2+, this effect was independent of oxygen (and hence HbS polymerisation and RBC sickling) but required extracellular Ca2+. The effect was completely abolished when Zn2+ (100 μM) was added to RBCs suspended in autologous plasma, implying a requirement of high levels of free Zn2+.
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Affiliation(s)
- U M Cytlak
- Department of Veterinary Medicine, Madingley Road, Cambridge, CB3 0ES, UK
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18
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Milligan C, Rees DC, Ellory JC, Osei A, Browning JA, Hannemann A, Gibson JS. A non-electrolyte haemolysis assay for diagnosis and prognosis of sickle cell disease. J Physiol 2013; 591:1463-74. [PMID: 23297308 PMCID: PMC3607166 DOI: 10.1113/jphysiol.2012.246579] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Red blood cells (RBCs) from patients with sickle cell disease (SCD) lyse in deoxygenated isosmotic non-electrolyte solutions. Haemolysis has features which suggest that it is linked to activation of the pathway termed Psickle. This pathway is usually described as a non-specific cationic conductance activated by deoxygenation, HbS polymerisation and RBC sickling. The current work addresses the hypothesis that this haemolysis will provide a novel diagnostic and prognostic test for SCD, dependent on the altered properties of the RBC membrane resulting from HbS polymerisation. A simple test represented by this haemolysis assay would be useful especially in less affluent deprived areas of the world where SCD is most prevalent. RBCs from HbSS and most HbSC individuals showed progressive lysis in deoxygenated isosmotic sucrose solution at pH 7.4 to a level greater than that observed with RBCs from HbAS or HbAA individuals. Cytochalasin B prevented haemolysis. Haemolysis was temperature- and pH-dependent. It required near physiological temperatures to occur in deoxygenated sucrose solutions at pH 7.4. At pH 6, haemolysis occurred even in oxygenated samples. Haemolysis was reduced in patients on long-term (>5 months) hydroxyurea treatment. Several manoeuvres which stabilise soluble HbS (aromatic aldehydes o-vanillin or 5-hydroxymethyl, and urea) reduced haemolysis, an effect not due to increased oxygen affinity. Conditions designed to elicit HbS polymerisation in cells from sickle trait patients (deoxygenated hyperosmotic sucrose solutions at pH 6) supported their haemolysis. These findings are consistent with haemolysis requiring HbS polymerisation and support the hypothesis that this may be used as a test for SCD.
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Affiliation(s)
- C Milligan
- Department of Veterinary Medicine, Madingley Road, Cambridge CB3 0ES, UK
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19
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Ma YL, Rees DC, Gibson JS, Ellory JC. The conductance of red blood cells from sickle cell patients: ion selectivity and inhibitors. J Physiol 2012; 590:2095-105. [PMID: 22411011 DOI: 10.1113/jphysiol.2012.229609] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The abnormally high cation permeability in red blood cells (RBCs) from patients with sickle cell disease (SCD) occupies a central role in pathogenesis. Sickle RBC properties are notably heterogeneous, however, thus limiting conventional flux techniques that necessarily average out the behaviour of millions of cells. Here we use the whole-cell patch configuration to characterise the permeability of single RBCs from patients with SCD in more detail. A non-specific cation conductance was reversibly induced upon deoxygenation and was permeable to both univalent (Na+, K+, Rb+) and also divalent (Ca2+, Mg2+) cations. It was sensitive to the tarantula spider toxin GsMTx-4. Mn2+ caused partial, reversible inhibition. The aromatic aldehyde o-vanillin also irreversibly inhibited the deoxygenation-induced conductance, partially at 1mM and almost completely at 5mM. Nifedipine, amiloride and ethylisopropylamiloride were ineffective. In oxygenated RBCs, the current was pH sensitive showing a marked increase as pH fell from 7.4 to 6, with no change apparent when pH was raised from 7.4 to 8. The effects of acidification and deoxygenation together were not additive. Many features of this deoxygenation-induced conductance (non-specificity for cations, permeability toCa2+ andMg2+, pH sensitivity, reversibility, partial inhibition by DIDS and Mn2+) are shared with the flux pathway sometimes referred to as Psickle. Sensitivity to GsMTx-4 indicates its possible identity as a stretch-activated channel. Sensitivity to o-vanillin implies that activation requires HbS polymerisation but since the conductance was observed in whole-cell patches, results suggest that bulk intracellular Hb is not involved; rather a membrane-bound subfraction is responsible for channel activation. The ability to record P(sickle)-like activity in single RBCs will facilitate further studies and eventual molecular identification of the pathway involved.
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Affiliation(s)
- Y-L Ma
- Department of Physiology, Anatomy & Genetics, Oxford, UK
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20
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Dalibalta S, Ellory JC, Browning JA, Wilkins RJ, Rees DC, Gibson JS. Novel permeability characteristics of red blood cells from sickle cell patients heterozygous for HbS and HbC (HbSC genotype). Blood Cells Mol Dis 2010; 45:46-52. [PMID: 20227897 DOI: 10.1016/j.bcmd.2010.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Accepted: 01/19/2010] [Indexed: 11/19/2022]
Abstract
Individuals heterozygous for HbS and HbC (HbSC) represent about 1/3(rd) of sickle cell disease (SCD) patients. Whilst HbSC disease is generally milder, there is considerable overlap in symptoms with HbSS disease. HbSC patients, as well as HbSS ones, present with the chronic anaemia and panoply of acute vaso-occlusive complications that characterize SCD. However, there are important clinical and haematological differences. Certain complications occur with greater frequency in HbSC patients (like proliferative retinopathy and osteonecrosis) whilst intravascular haemolysis is reduced. Patients with HbSC disease can be considered as a discrete subset of SCD cases. Although much work has been carried out on understanding the pathogenesis of SCD in HbSS homozygotes, including the contribution of altered red blood cell permeability, relatively little pertains directly to HbSC individuals. Results reported in the literature suggest that HbSC cells, and particularly certain subpopulations, present with similar permeability to HbSS cells but there are also important differences - these have not been well characterized. We hypothesise that their unique cell transport properties accounts for the different pattern of disease in HbSC patients and represents a potential chemotherapeutic target not shared in red blood cells from HbSS patients. The distinct pattern of clinical haematology in HbSC disease is emphasised here. We analyse some of the electrophysiological properties of single red blood cells from HbSC patients, comparing them with those from HbSS patients and normal HbAA individuals. We also use the isosmotic haemolysis technique to investigate the behaviour of total red blood cell populations. Whilst both HbSS and HbSC cells show increased monovalent and divalent (Ca(2+)) cation conductance further elevated upon deoxygenation, the distribution of current magnitudes differs, and outward rectification is greatest for HbSC cells. In addition, although Gd(3+) largely abolishes the cation conductance of both HbSS and HbSC cells, only in HbSS ones are currents inhibited by the aminoglycosides like streptomycin. This distinction is retained in isosmotic lysis experiments where both HbSS and HbSC cells undergo haemolysis in sucrose solutions but streptomycin significantly inhibits lysis only in HbSS cells. These findings emphasise similarities but also differences in the permeability properties of HbSS and HbSC cells, which may be important in pathogenesis.
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Affiliation(s)
- S Dalibalta
- Department of Physiology, Anatomy & Genetics, Parks Road, Oxford, OX1 3PT, UK.
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21
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Ellory JC, Sequeira R, Constantine A, Wilkins RJ, Gibson JS. Non-electrolyte permeability of deoxygenated sickle cells compared. Blood Cells Mol Dis 2008; 41:44-9. [PMID: 18456522 DOI: 10.1016/j.bcmd.2008.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 03/18/2008] [Indexed: 11/20/2022]
Abstract
The passive permeability pathways of red cells are poorly defined, with the exception of the Gardos channel. Several cation and anion pathways can be induced by a variety of manoeuvres, however, including treatment with oxidants, low ionic strength (LIS), shrinkage, swelling and also infection with the intra-erythrocytic malaria parasite. Several of these stimuli (malaria, swelling, LIS), in addition, also activate a non-electrolyte this permeability. Sickle cells uniquely show a deoxygenation-induced pathway, which is termed P(sickle) and is usually considered to be a conductive cationic pathway. In this report, we explore further the extent to which this permeability pathway of deoxygenated sickle cells is available for non-electrolyte transport. We show that a number of solutes are permeable, with greater permeability to sugars (notably lactose and maltose) and smaller molecules, and less to charged or zwitterionic species. Red cells from heterozygous HbSC patients also showed deoxygenation-induced haemolysis in isosmotic sucrose solution, though to a slightly lesser extent than for red cells from homozygous sickle cell patients. In contrast to sickle cells, red cells from beta-thalassaemic patients did not show haemolysis in isosmotic sucrose solutions, regardless of the O(2) tension. Of the secondary cellular changes resulting from incubation in non-electrolyte solutions (which include imposition of a highly positive membrane potential, marked intracellular alkalinisation and cell shrinkage), none appear to correlate with activation of the non-electrolyte permeability. Rather, findings indicate that it is low ionic strength per se that is responsible. Normal red cells also show changes in ionic and non-electrolyte permeability in low ionic strength media, and these permeabilities are compared to those found in deoxygenated sickle cells. The extent to which these different permeabilities in normal and sickle red cells can be ascribed to one or more common pathways remains to be determined.
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Affiliation(s)
- J C Ellory
- Department of Physiology, Anatomy and Genetics, Parks Road, Oxford, OX1 3PT, UK.
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22
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Gibson JS, Milner PI, White R, Fairfax TPA, Wilkins RJ. Oxygen and reactive oxygen species in articular cartilage: modulators of ionic homeostasis. Pflugers Arch 2007; 455:563-73. [PMID: 17849146 DOI: 10.1007/s00424-007-0310-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 06/20/2007] [Indexed: 11/26/2022]
Abstract
Articular cartilage is an avascular tissue dependent on diffusion mainly from synovial fluid to service its metabolic requirements. Levels of oxygen (O(2)) in the tissue are low, with estimates of between 1 and 6%. Metabolism is largely, if not entirely, glycolytic, with little capacity for oxidative phosphorylation. Notwithstanding, the tissue requires O(2) and consumes it, albeit at low rates. Changes in O(2) tension also have profound effects on chondrocytes affecting phenotype, gene expression, and morphology, as well as response to, and production of, cytokines. Although chondrocytes can survive prolonged anoxia, low O(2) levels have significant metabolic effects, inhibiting glycolysis (the negative Pasteur effect), and also notably matrix production. Why this tissue should respond so markedly to reduction in O(2) tension remains a paradox. Ion homeostasis in articular chondrocytes is also markedly affected by the extracellular matrix in which the cells reside. Recent work has shown that ion homeostasis also responds to changes in O(2) tension, in such a way as to produce significant effects on cell function. For this purpose, O(2) probably acts via alteration in levels of reactive oxygen species. We discuss the possibility that O(2) consumption by this tissue is required to maintain levels of ROS, which are then used physiologically as an intracellular signalling device. This postulate may go some way towards explaining why the tissue is dependent on O(2) and why its removal has such marked effects. Understanding the role of oxygen has implications for disease states in which O(2) or ROS levels may be perturbed.
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Affiliation(s)
- J S Gibson
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, England
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23
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Ellory JC, Robinson HC, Browning JA, Stewart GW, Gehl KA, Gibson JS. Abnormal permeability pathways in human red blood cells. Blood Cells Mol Dis 2007; 39:1-6. [PMID: 17434766 DOI: 10.1016/j.bcmd.2007.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Accepted: 02/19/2007] [Indexed: 01/29/2023]
Abstract
A number of situations that result in abnormal permeability pathways in human red blood cells (RBCs) have been investigated. In sickle cell disease (SCD), RBCs contain HbS, rather than the normal HbA. When deoxygenated, an abnormal conductance pathway, termed P(sickle), is activated, which contributes to cell dehydration, largely through allowing Ca(2+) entry and subsequent activation of the Gardos channel. Whole-cell patch-clamp recordings from sickle RBCs show a deoxygenated-induced conductance, absent from normal RBCs, which shares some of the properties of P(sickle): equivalent Na(+) and K(+) permeability, significant Ca(2+) conductance, partial inhibition by DIDS and also Zn(2+). Gd(3+) markedly attenuates conductance in both normal and sickle RBCs. In addition, deoxygenated sickle cells, but not oxygenated ones or normal RBCs regardless of the oxygen tension, undergo haemolysis in isosmotic non-electrolyte solutions. Non-electrolyte entry was confirmed radioisotopically whilst haemolysis was inhibited by DIDS. These findings suggest that under certain circumstances P(sickle) may also be permeable to non-electrolytes. Finally, RBCs from certain patients with hereditary stomatocytosis have a mutated band 3, which appears able to act as a conductance pathway for univalent cations. These results extend our understanding of the abnormal permeability pathways of RBCs.
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Affiliation(s)
- J C Ellory
- Department of Physiology, Anatomy and Genetics, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK
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24
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Milner PI, Wilkins RJ, Gibson JS. The role of mitochondrial reactive oxygen species in pH regulation in articular chondrocytes. Osteoarthritis Cartilage 2007; 15:735-42. [PMID: 17306992 DOI: 10.1016/j.joca.2007.01.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 01/06/2007] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To examine the effect of O(2) and the role, and source, of reactive oxygen species (ROS) on pH regulation in articular chondrocytes. METHODS Cartilage from equine metacarpo/tarsophalangeal joints was digested (collagenase) to isolate chondrocytes and loaded with 2',7'-bis-2-(carboxyethyl)-5(6)-carboxylfluorescein, a pH-sensitive fluorophore. O(2) tension was maintained using Eschweiler tonometers and a Wosthoff gas mixer. Cells were exposed to agents which alter ROS levels, mitochondrial inhibitors and/or inhibitors of protein phosphorylation. ROS levels were determined by dichlorofluorescein and mitochondrial membrane potential measured using JC-1. RESULTS pH homeostasis was dependent on ROS. Na(+)/H(+) exchanger (NHE) activity was inhibited at low O(2) tension (acid efflux reducing from 2.30+/-0.05 to 1.27+/-0.11mMmin(-1) at 1%). NHE activity correlated with ROS levels (r(2)=0.65). ROS levels were increased by antimycin A (with levels at 1% O(2) tension increasing from 59+/-9% of the value at 20% to 87+/-7%), but reduced by rotenone, myxothiazol and diphenyleneiodonium. Hypoxia induced depolarisation of the mitochondrial membrane potential (with JC-1 red-green fluorescence ratio at 1% O(2) tension decreasing to 40+/-10% of the value at 20%). The response to changes in O(2) and to antimycin A was inhibited by staurosporine, wortmanin and calyculin A. CONCLUSION The fall in ROS levels in hypoxia reduces the ability of articular chondrocytes to regulate pH, inhibiting NHE activity via changes in protein phosphorylation. The site of ROS generation is likely to be mitochondrial electron transport chain complex III. These effects are important to understanding normal chondrocyte function and response to altered O(2) tension.
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Affiliation(s)
- P I Milner
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
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25
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Lloyd S, Gibson JS. Haematology and biochemistry in healthy young pheasants and red-legged partridges and effects of spironucleosis on these parameters. Avian Pathol 2007; 35:335-40. [PMID: 16854649 DOI: 10.1080/03079450600821794] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Plasma biochemical and haematological parameters were examined in 4-week-old to 12-week-old game birds. Healthy, uninfected pheasants and partridges had similar levels of total protein, albumin, osmolality, Na+, Cl-, K+, Mg2+ and glucose. Triglyceride, globulin and Ca2+ were significantly higher and PO43- was lower in the partridges. Pheasants carrying a light to moderate infection with Spironucleus had significantly lower total protein, albumin, osmolality, Na+, Cl-, Ca2+ and PO43-. In severely affected pheasants, the osmolality, Na+ and Cl- fell further. Triglyceride and glucose were significantly lower than in healthy birds, and Mg2+ was higher. Similar data were obtained from infected partridges. Red cell parameters rose significantly in pheasants severely affected by spironucleosis, and the percent of heterophils was significantly higher and lymphocytes and basophils lower in their blood smears. The breast and leg muscle wet weight from severely affected pheasants was 22.2 and 37.7% that of uninfected birds, although the water content of the breast muscle was significantly higher.
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Affiliation(s)
- S Lloyd
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, UK.
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Milner PI, Fairfax TPA, Browning JA, Wilkins RJ, Gibson JS. The effect of O2 tension on pH homeostasis in equine articular chondrocytes. ACTA ACUST UNITED AC 2006; 54:3523-32. [PMID: 17075856 DOI: 10.1002/art.22209] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To determine the effects of varying O(2) on pH homeostasis, based on the hypothesis that the function of articular chondrocytes is best understood at realistic O(2) tensions. METHODS Cartilage from equine metacarpophalangeal/tarsophalangeal joints was digested with collagenase to isolate chondrocytes, and then loaded with the pH-sensitive fluorophore 2',7'-bis-2-(carboxyethyl)-5(6)-carboxylfluorescein. The radioisotope(22)Na(+) was used to determine the kinetics of Na(+)/H(+) exchange (NHE) and the activity of the Na(+)/K(+) pump, and ATP levels were assessed with luciferin assays. Levels of reactive oxygen species (ROS) were determined using 2',7'-dichlorofluorescein diacetate. RESULTS The pH homeostasis was unaffected when comparing tissue maintained at 20% O(2) (the level in water-saturated air at 37 degrees C) with that at 5% O(2) (which approximates the normal level in healthy cartilage); however, an O(2) tension of <5% caused a fall in intracellular pH (pH(i)) and slowed pH(i) recovery following acidification, an effect mediated via inhibition of NHE activity (likely through acid extrusion by NHE isoform 1). The Na(+)/K(+) pump activity and intracellular ATP concentration were unaffected by hypoxia, but the levels of ROS were reduced. Hypoxic inhibition of NHE activity and the reduction in ROS levels were reversed by treatment with H(2)O(2), Co(2+), or antimycin A. Treatment with calyculin A also prevented hypoxic inhibition of NHE activity. CONCLUSION The ability of articular chondrocytes to carry out pH homeostasis is compromised when O(2) tensions fall below those normally experienced, via inhibition of NHE. The putative signal is a reduction in levels of ROS derived from mitochondria, acting via altered protein phosphorylation. This effect is relevant to both physiologic and pathologic states of lowered O(2), such as in chronic inflammation.
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Abstract
Absorption of fluid by the small intestine of 4-week-old to 12-week-old farmed pheasants and partridges has been studied using an inverted sac technique. The mean rate of absorption was 54 +/- 4 (mean +/- standard error of the mean) microl/g dry tissue/min in pheasants and 49 +/- 3 microl/g dry tissue/min in partridges. Use of inhibitors and ion substitution suggested transepithelial transport driven by baso-lateral Na+/K+ pumps, in combination with mucosal Na+-coupled transporters, including Cl(-)-coupled transporters. Absorption was more than halved to 17 +/- 2 microl/g dry tissue/min (P < 0.001) in birds that were very heavily infected with Spironucleus spp. in their small intestine and showing a syndrome of diarrhoea, depression and loss of weight to severe emaciation. Birds carrying light to moderate levels of infection with Spironucleus had very variable rates of absorption that were statistically similar to the controls. Doubling the glucose concentration in the buffer to 40 mM significantly enhanced absorption.
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Affiliation(s)
- S Lloyd
- Department of Veterinary Medicine, University of Cambridge, UK.
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Haist SA, Wilson JF, Lineberry MJ, Gibson JS, Griffith CH. 344 A RANDOMIZED CONTROL TRIAL USING INSINUATED STANDARDIZED PATIENTS TO ASSESS RESIDENTS' DOMESTIC VIOLENCE SKILLS: A PILOT STUDY. J Investig Med 2005. [DOI: 10.2310/6650.2005.00006.343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Lineberry MJ, Wilson JF, Gibson JS, Griffith CH, Haist SA. 350 OBSTACLES TO EVALUATING RESIDENTS USING UNANNOUNCED STANDARDIZED PATIENTS. J Investig Med 2005. [DOI: 10.2310/6650.2005.00006.349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Haist SA, Jessup ML, Gibson JS, Griffith CH, Wilson JF. 140 DOES A DOMESTIC VIOLENCE OR A DEPRESSION WORKSHOP USING STANDARDIZED PATIENTS IMPROVE CLINICAL SKILLS OR INCREASE KNOWLEDGE LONG-TERM? J Investig Med 2004. [DOI: 10.1136/jim-52-suppl1-693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Jessup ML, Gibson JS, Wilson JF, Griffith CH, Haist SA. 259 A DOMESTIC VIOLENCE WORKSHOP USING STANDARDIZED PATIENTS IMPROVES CLINICAL SKILLS AND KNOWLEDGE. J Investig Med 2004. [DOI: 10.1136/jim-52-suppl1-812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Abstract
REASONS FOR PERFORMING STUDY Ca2+ homeostasis in articular chondrocytes affects synthesis and degradation of the cartilage matrix, as well as other cellular functions, thereby contributing to joint integrity. Although it will be affected by mechanical loading, the sensitivity of intracellular Ca2+ concentration ([Ca2+]i) in equine articular chondrocytes to many stimuli remains unknown. HYPOTHESIS An improved understanding of Ca2+ homeostasis in equine articular chondrocytes, and how it is altered during joint loading and pathology, will be important in understanding how joints respond to mechanical loads. METHODS [Ca2+]i was determined using the fluorophore fura-2. We examined the effects of hypotonic shock, a perturbation experienced in vivo during mechanical loading cycles. We used inhibitors of Ca2+ transporters to ascertain the important factors in Ca2+ homeostasis. RESULTS Under isotonic conditions, [Ca2+]i was 148 +/- 23 nmol/l, increasing by 216 +/- 66 nmol/l in response to reduction in extracellular osmolality of 50%. Resting [Ca2+]i, and the increase following hypotonic shock, were decreased by Ca2+ removal; they were both elevated when extracellular [Ca2+] ([Ca2+]o) was raised or following Na+ removal. The hypotonicity-induced rise in [Ca2+]i was inhibited by exposure of cells to gadolinium (Gd3+; 10 micromol/l), an inhibitor of mechanosensitive channels. [Ca2+]i was also elevated following treatment of cells with thapsigargin (10 micromol/l), an inhibitor of the Ca2+ pump of intracellular stores. CONCLUSIONS A model is presented which interprets these findings in relation to Ca2+ homeostasis in equine articular chondrocytes, including the presence of mechanosensitive channels allowing Ca2+ entry, a Na+/Ca2+ exchanger for removal of intracellular Ca2+ and intracellular stores sensitive to thapsigargin. POTENTIAL RELEVANCE A more complete understanding of Ca2+ homeostasis in equine chondrocytes may allow development of future therapeutic regimes to ameliorate joint disease.
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Affiliation(s)
- R J Wilkins
- University of Oxford, University Laboratory of Physiology, Parks Road, Oxford OX1 3PT, UK
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Abstract
1-Chloro-2,4-dinitrobenzene (CDNB), which causes oxidative stress through depletion of reduced glutathione (GSH), increases the passive K+ permeability of red cells. In this paper, we investigated the effects of CDNB (1 mM) on the activities of the K+-Cl- cotransporter (KCC; measured as Cl--dependent K+ influx) and the Gardos channel (taken as clotrimazole-sensitive K+ influx, 5 microM) in human red cells, using 86Rb+ as a K+ congener. 45Ca2+ was used to study passive Ca2+ entry and active Ca2+ efflux via the plasma membrane Ca2+ pump. Both the Gardos channel and KCC were stimulated in both normal and sickle red cells. In sickle cells, stimulation of KCC was similar in oxygenated and deoxygenated cells; that of the Gardos channel was greater in deoxygenated cells. In normal red cells, stimulation of both pathways was greater in oxygenated cells (by 4 +/- 1-fold; all means +/- S.E.M., n = 3). The effects on the Gardos channel were dependent on extracellular Ca2+ and were associated with inhibition of the plasma membrane Ca2+ pump (by 29 +/- 3 %, P < 0.01) and increased Ca2+ sensitivity of the channel (EC50 for [Ca2+]i reduced from 260 +/- 26 to 175 +/- 15 nM; P < 0.05). Cell volume, pHi, ATP levels and passive Ca2+ entry were not affected by CDNB. The effects on KCC were inhibited (93 +/- 6 %) by prior treatment with the protein phosphatase inhibitor calyculin A (100 nM) and were not additive with stimulation by N-ethylmaleimide (1 mM), regardless of the order of addition. These findings are therefore consistent with inhibition of a regulatory protein kinase, although stimulation of the conjugate protein phosphatase(s) may also occur. KCC stimulation was also Ca2+ dependent. These findings are important for understanding how GSH depletion alters membrane permeability and how to protect against red cell dehydration.
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Affiliation(s)
- M C Muzyamba
- Department of Clinical Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
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Kiessling K, Roberts N, Gibson JS, Ellory JC. A comparison in normal individuals and sickle cell patients of reduced glutathione precursors and their transport between plasma and red cells. Hematol J 2002; 1:243-9. [PMID: 11920197 DOI: 10.1038/sj.thj.6200033] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/1999] [Accepted: 03/14/2000] [Indexed: 11/09/2022]
Abstract
INTRODUCTION Reduced glutathione is an important antioxidant in red cells whose depletion may contribute to the pathophysiology of sickle cell disease. The current study was designed to examine the availability of reduced glutathione precursors (glutamate, cysteine, glycine and possibly glutamine) together with the activity of the main transport pathways for their uptake (system ASC for cysteine and glycine; system gly for glycine). MATERIALS AND METHODS Blood samples were obtained from normal (HbAA, HbA cells) and sickle cell disease patients (HbSS, HbS cells); amino acids were measured by HPLC; and transporter activity was measured by radioactive tracer fluxes (using serine and glycine for activity of system ASC; and glycine for that of system gly). RESULTS Plasma concentrations of cysteine and glycine were increased and concentrations of all amino acids were elevated in HbS cells. The activity of system ASC was increased in HbS cells (both transport capacity and affinity were elevated for serine transport; transport capacity only for glycine). Activity of system gly was also increased (twofold increase in V(max) for glycine flux), though not significantly. Oxygenation also increased the activity of both transporters in normal and HbS cells. CO prevented deoxy-inhibition of glycine transport. Staurosporine (5 microM) inhibited O(2)-stimulated glycine transport through system ASC. It also inhibited the absolute magnitude of transport through system gly, but the O(2)-dependent flux was unaffected. CONCLUSION Low reduced glutathione levels in HbS cells were not due to decreased substrate availability and O(2) stimulated transport of reduced glutathione precursors in both normal and HbS cells, through a mechanism that is likely to involve Hb and possibly protein phosphorylation.
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Affiliation(s)
- K Kiessling
- University Laboratory of Physiology, Parks Road, Oxford, OX1 3PT, UK
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Abstract
We have reviewed here a number of membrane transport events in red cells from normal individuals and sickle cell patients which respond to changes in O(2) tension. Some deoxygenation-induced changes in membrane permeability are unique to HbS cells and contribute to their dehydration and subsequent sickling. Polymerization of HbS, or specific oxidant damage (or altered redox potential), is a likely factor underlying the abnormal behavior. The key regulatory sites within the membrane or associated proteins remain uncertain and their identity will form the focus of future research. A model for sickle cell dehydration is presented. Inhibition of these permeability changes represents possible avenues for future chemotherapy to ameliorate the condition.
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Affiliation(s)
- J S Gibson
- Department of Clinical Veterinary Medicine, University of Cambridge, United Kingdom.
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Abstract
There are many examples of O2-sensitive solute transport in vertebrate red cells. The response is selective, specific, and conserved across the entire vertebrate spectrum. A number of possible physiological roles have been proposed, but abnormal responses to O2 may also be important pathologically. Significant alterations in O2 dependence of red cell cation transport are observed in sickle cell disease (and also following exposure to oxidants) and probably contribute to its pathophysiology. In this paper, we review some of the features of O2-sensitive solute transporters in red cells and possible reasons for the abnormal response in sickle cells. Our aim is to identify specific, novel pharmacological inhibitors of these abnormal pathways and thereby ameliorate the disease.
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Affiliation(s)
- J S Gibson
- Department of Physiology, University of London, London, Tooting, SW17 0RE, United Kingdom.
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Gibson JS, Speake PF, Muzyamba MC, Husain F, Luckas MC, Ellory JC. K(+) transport in red blood cells from human umbilical cord. Biochim Biophys Acta 2001; 1512:231-8. [PMID: 11406100 DOI: 10.1016/s0005-2736(01)00323-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The current study was designed to characterise K(+) transport in human fetal red blood cells, containing mainly haemoglobin F (HbF, and termed HbF cells), isolated from umbilical cords following normal parturition. Na(+)/K(+) pump activity was comparable to that in normal adult human red cells (which contain HbA, and are termed HbA cells). Passive (ouabain-resistant) K(+) transport was dominated by a bumetanide (10 microM)-resistant component, inhibited by [(dihydroxyindenyl)oxy]alkanoic acid (100 microM), calyculin A (100 nM) and Cl(-) removal, and stimulated by N-ethylmaleimide (1 mM) and staurosporine (2 microM) - all consistent with mediation via the K(+)-Cl(-) cotransporter (KCC). KCC activity in HbF cells was also O(2)-dependent and stimulated by swelling and urea, and showed a biphasic response to changes in external pH. Peak activity of KCC in HbF cells was about 3-fold that in HbA cells. These characteristics are qualitatively similar to those observed in HbA cells, notwithstanding the different conditions experienced by HbF cells in vivo, and the presence of HbF rather than HbA. KCC in HbF cells has a higher total capacity, but when measured at the ambient PO(2) of fetal blood it would be similar in magnitude to that in fully oxygenated HbA cells, and about that required to balance K(+) accumulation via the Na(+)/K(+) pump. These findings are relevant to the mechanism by which O(2) regulates membrane transporters in red blood cells, and to the strategy of promoting HbF synthesis as a therapy for patients with sickle cell disease.
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Affiliation(s)
- J S Gibson
- Department of Physiology, St. George's Hospital Medical School, University of London, UK.
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Gibson JS, Khan A, Speake PF, Ellory JC. O2 dependence of K+ transport in sickle cells: the effect of different cell populations and the substituted benzaldehyde 12C79. FASEB J 2001; 15:823-32. [PMID: 11259401 DOI: 10.1096/fj.00-0177com] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The molecular basis of sickle cell disease (SCD) is well known but the pathophysiology is poorly understood. It remains intractable to therapy. Hyperactivity of several membrane transport systems, including the K+-Cl- cotransporter (termed KCC), cause HbS-containing red cells (termed HbS cells) to dehydrate and sickle, leading to the development of sickle cell crises (SCCs). Contrary to normal red cells (HbA cells), KCC in HbS cells is active at low O2 tensions (PO2s), remaining responsive to low pH or urea. Since these stimuli are usually encountered in hypoxic regions, the abnormal O2 dependence increases the contribution of KCC to dehydration, and hence development of SCCs. These differences with HbA cells may be due to the younger population of cells or to polymerization of HbS. We used 86Rb+ as a K+ congener to investigate the activity of KCC at different PO2s, and density gradient separation to investigate different red cell fractions. We found no correlation of O2 dependence with cell fractions. We also used the substituted benzaldehyde 12C79 to increase the O2 affinity of HbS and found that its effect on HbS O2 saturation and cell sickling correlated with that on both Cl--independent and Cl--dependent K+ transport, implying that, at low PO2s, KCC activity correlated with HbS polymerization. The importance of these results to understanding the pathophysiology of SCD, and for the design of chemotherapeutic agents to ameliorate or prevent SCC, is discussed.
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Affiliation(s)
- J S Gibson
- Department of Physiol., St. George's Hospital Medical School, University of London, Tooting, SW17 0RE, UK.
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Campbell EH, Ellory JC, Gibson JS. Effects of protein kinase and phosphatase inhibitors and anti-L antisera on K+ transport in LK sheep red cells. Bioelectrochemistry 2000; 52:151-9. [PMID: 11129238 DOI: 10.1016/s0302-4598(00)00097-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the role of protein phosphorylation in the action of anti-L on low potassium (LK) sheep red cells. Anti-L stimulated the Na/K pump by four- to fivefold, but Na/K pump activity in anti-L-stimulated or in control cells was unaffected by protein kinase/protein phosphatase (PK/PP) inhibitors. KCl co-transport activity was inhibited by anti-L (about 50%). Co-transport was stimulated by staurosporine; and inhibited by calyculin A, okadaic acid, tyrphostin B46 and genistein; with a similar pattem in both control and anti-L-treated cells. O2 sensitivity of KCl co-transport was similar in control and anti-L-treated cells. Neither control nor anti-L-stimulated Na/K pump activities were O2 sensitive. Incubation with urea stimulated KCl co-transport in both control and anti-L-treated cells. Inhibition of co-transport by anti-L was unaffected by low concentrations of urea but was reduced at higher urea concentrations. Na/K pump activity of control cells was unaffected by incubation with urea, but that in cells stimulated by anti-L was reduced, though not significantly. Under high hydrostatic pressure, KCl co-transport was stimulated, and the inhibitory effects of PP inhibition (okadaic acid), anti-L or combinations of the two were reduced. Results suggest that anti-L does not affect K+ transport in LK sheep red cells via protein phosphorylation.
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Affiliation(s)
- E H Campbell
- Department of Veterinary Preclinical Sciences, University of Liverpool, UK
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40
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Abstract
The effect of oxidants on K(+)-Cl(-) cotransport (KCC) was investigated in equine red blood cells. Carbon monoxide mimicked O(2). The substituted benzaldehyde, 12C79 (5 mM), markedly increased O(2) affinity. In N(2), however, O(2) saturation was low (<10%) but KCC remained active. Nitrite (NO(2)(-)) oxidized heme to methemoglobin (metHb). High concentrations of NO(2)(-) (1 and 5 mM vs. 0.5 mM) increased KCC activity above control levels; it became O(2) independent but remained sensitive to other stimuli. 1-Chloro-2, 4-dinitrobenzene (1-3 mM) depleted reduced glutathione (GSH). Prolonged exposure (60-120 min, 1 mM) or high concentrations (3 mM) stimulated an O(2)-independent KCC activity; short exposures and low concentrations (30 min, 0.5 or 1 mM) did not. The effect of these manipulations was correlated with changes in GSH and metHb concentrations. An oxy conformation of Hb was necessary for KCC activation. An increase in its activity over the level found in oxygenated control cells required both accumulation of metHb and depletion of GSH. Findings are relevant to understanding the physiology and pathology of regulation of KCC.
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Affiliation(s)
- M C Muzyamba
- Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool L69 7ZJ, United Kingdom
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Abstract
Dimethyl adipimidate (DMA) reduces K+ loss from, and dehydration of, red cells containing haemoglobin S (HbS cells). Three membrane transporters may contribute to these processes: the deoxygenation-induced cation-selective channel (Psickle), the Ca2+-activated K+ channel (or Gardos channel) and the K+-CI- cotransporter (KCC). We show that DMA inhibited all three pathways in deoxygenated HbS cells. The Gardos channel could be activated following Ca2+ loading. Considerable KCC activity was present in oxygenated HbS cells, showing a selective action of DMA on the transporter in deoxygenated cells. Inhibition of sickling correlated strongly with that of Psickle and moderately with that of KCC activity. We conclude that DMA does not inhibit the K+ pathways directly, but acts mainly by preventing HbS polymerisation and sickling. These findings are relevant to the development of novel chemotherapeutic agents for amelioration of sickle cell disease.
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Affiliation(s)
- J S Gibson
- Department of Physiology, St George's Hospital Medical School, University of London, Cranmer Terrace, UK.
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Abstract
A class of adaptive-optics problems is described in which phase distortions caused by atmospheric turbulence are corrected by adaptive wave-front reconstruction with a deformable mirror, i.e., the control loop that drives the mirror adapts in real time to time-varying atmospheric conditions, as opposed to the linear time-invariant control loops used in conventional adaptive optics. The basic problem is posed as an adaptive disturbance-rejection problem with many channels. The solution given is an adaptive feedforward control loop built around a multichannel adaptive lattice filter. Simulation results are presented for a 1-m telescope with both one-layer and two-layer atmospheric turbulence profiles. These results demonstrate the significant improvement in imaging resolution produced by the adaptive control loop compared with a classical linear time-invariant control loop.
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Affiliation(s)
- J S Gibson
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095-1597, USA.
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Abstract
In this paper a mathematical model is developed to describe the effect of nonuniform growth on the mechanical stress experienced by cells within an avascular tumour. The constitutive law combines the stress-strain relation of linear elasticity with a growth term that is derived by analogy with thermal expansion. To accommodate the continuous nature of the growth process, the law relates the rate of change of the stress tensor to the rate of change of the strain (rather than relating the stress to the strain directly). By studying three model problems which differ in detail, certain characteristic features are identified. First, cells near the tumour boundary, where nutrient levels and cell proliferation rates are high, are under compression. By contrast, cells towards the centre of the tumour, where nutrient levels are low and cell death dominant, are under tension. The implications of these results and possible model developments are also discussed.
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Affiliation(s)
- A F Jones
- Department of Mathematics, University of Manchester, UK
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Abstract
The H-Tx rat is a genetic model of hydrocephalus for which thereis a poor understanding of the mode of inheritance. Previous studies suggested a polygenicmode of inheritance but the breeding data to supportthis hypothesis have not been reported. In an attempt to clarify the hereditary mode we have analyzed the data from eight generations of H-Tx rats and four generations of cross-matings between H-Tx rats and Sprague-Dawley (SD) rats. In the H-Tx rat colony 113 of 129 random brother-sister matings (87.60%) produced hydrocephalic offspring, with males and females being equally affected. The overall incidence varied greatly with an average of 30. 35%. In matings with more than three litters, all mating pairs yielded hydrocephalic pups. In cross-matings both hydrocephalic and normal H-Tx rats were mated with normal SD rats. No hydrocephalus was observed in the first generation of 124 pups (F1). Subsequent brother-sister matings of F1 animals generated hydrocephalic pups in the F2 generation with a lower incidence (4.67% in hydrocephalic HTx/SD matings and 5.11% in normal HTx/SD matings, respectively) than in the H-Tx rat colony (30.35%). Back-cross-matings between F2 rats and normal H-Tx rats yielded an incidence of hydrocephalus higher than that of the cross-matings but lower than that of the H-Tx colony. These data strongly suggest that the H-Tx rat is a homozygous carrier of an autosomal recessive hydrocephalus gene with incomplete penetrance. Furthermore, the data clearly rule out sex-linked and polygenic modes of inheritance and provide further insight with respect to genetic inheritance of hydrocephalus.
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Affiliation(s)
- X Cai
- Wade's Center for Hydrocephalus, Health Research Institute, Orlando Regional Healthcare System, Orlando, Florida 32806, USA.
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45
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Abstract
Oxygen is essential for all higher forms of animal life. It is required for oxidative phosphorylation, which forms the bulk of the energy supply of most animals. In many vertebrates, transport of O(2) from respiratory to other tissues, and of CO(2) in the opposite direction, involves red cells. These are highly specialised, adapted for their respiratory function. Intracellular haemoglobin, carbonic anhydrase and the membrane anion exchanger (AE1) increase the effective O(2)- and CO(2)-carrying capacity of red cells by approximately 100-fold. O(2) also has a pathological role. It is a very reactive species chemically, and oxidation, free radical generation and peroxide formation can be major hazards. Cells that come into contact with potentially damaging levels of O(2) have a variety of systems to protect them against oxidative damage. Those in red cells include catalase, superoxide dismutase and glutathione. In this review, we focus on a third role of O(2), as a regulator of membrane transport systems, a role with important consequences for the homeostasis of the red cell and also the organism as a whole. We show that regulation of red cell transporters by O(2) is widespread throughout the vertebrate kingdom. The effect of O(2) is selective but involves a wide range of transporters, including inorganic and organic systems, and both electroneutral and conductive pathways. Finally, we discuss what is known about the mechanism of the O(2) effect and comment on its physiological and pathological roles.
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Affiliation(s)
- J S Gibson
- Veterinary Preclinical Sciences and School of Biological Sciences, University of Liverpool, Liverpool L69 3BX, UK.
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Abstract
Transforming growth factor-beta1 (TGF-beta1) is a cytokine with diverse biological effects. Overexpression of TGF-beta1 in mice has been shown to induce progressive hydrocephalus. We have used a quantitative RT-PCR method to analyze the TGF-beta1 expression in the brains of H-Tx rat, a model of congenital hydrocephalus. Our studies have shown that rather than increased expression, the 3- and 10-day hydrocephalic H-Tx rats have significantly lower TGF-beta1 levels than their normal siblings (p < 0.01). This difference became insignificant in the 21-day group. Besides, both hydrocephalic and normal H-Tx rats have significantly lower TGF-beta1 levels in all three age groups of 3-, 10- and 21-days than SD control rats (p < 0.01 in all three groups) although the difference tends to become less significant with development. We also tested the expression of another cytokine, the epidermal growth factor, and observed a similar reduction. This suggests that the TGF-beta1 expression change is not unique to the development of hydrocephalus in this rat model. Our hypothesis is that the TGF-beta1 expression decrease in the H-Tx rat is not the cause of the disease. Rather it might be the result of feedback inhibition by increase in the expression of the gene it regulates, including an extracellular matrix component. Effort is currently being made to test this hypothesis.
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Affiliation(s)
- X Cai
- Wade's Center for Hydrocephalus Research, Orlando Regional Health Research Institute, FL 32806, USA
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Vezakis A, Davides D, Gibson JS, Moore MR, Shah H, Larvin M, McMahon MJ. Randomized comparison between low-pressure laparoscopic cholecystectomy and gasless laparoscopic cholecystectomy. Surg Endosc 1999; 13:890-3. [PMID: 10449846 DOI: 10.1007/s004649901127] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Laparoscopic cholecystectomy using low-pressure pneumoperitoneum (8 mmHg) minimizes adverse hemodynamic effects, reduces postoperative pain, and accelerates recovery. Similar claims are made for gasless laparoscopy using abdominal wall lifting. The aim of this study was to compare gasless laparoscopic cholecystectomy to low-pressure cholecystectomy with respect to postoperative pain and recovery. METHODS Thirty-six patients were randomized to low-pressure or gasless laparoscopic cholecystectomy using a subcutaneous lifting system (Laparotenser). RESULTS The characteristics of the patients were similar in the two groups. The procedure was completed in all patients in the low-pressure group, but two patients in the gasless group were converted to pneumoperitoneum. There were no significant differences in postoperative pain and analgesic consumption, but patients in the gasless group developed shoulder pain more frequently (50% vs 11%, p < 0.05). Gasless operation took longer to perform (95 vs 72.5 min, p = 0.01). CONCLUSIONS Gasless and low-pressure laparoscopic cholecystectomy were similar with respect to postoperative pain and recovery. The gasless technique provided inferior exposure and the operation took longer, but the technique may still have value in high-risk patients with cardiorespiratory disease.
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Affiliation(s)
- A Vezakis
- Leeds Institute for Minimally Invasive Therapy, Academic Unit of Surgery, The General Infirmary at Leeds, Great George Street, Leeds LS1 3EX, UK
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48
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Abstract
1. Na+-K+-2Cl- cotransport (NKCC) was studied in turkey red cells using Na+ dependence or bumetanide sensitivity of 86Rb+ influx to monitor activity of the transporter. 2. Deoxygenation was the major physiological stimulus for NKCC activity: oxygen tensions (PO2) over the physiological range modulated the transporter, with a PO2 for half-maximal activation of about 41 mmHg (n = 3). In air, activity of NKCC was also stimulated by shrinkage and isoproteronol (isoprenaline, 5 microgr;M). By contrast, in deoxygenated cells, although the transporter activity was markedly elevated, it was no longer sensitive to volume or beta-adrenergic stimulation. 3. Calyculin A, a protein phosphatase inhibitor, stimulated cotransport with a lag of about 5 min. N-Ethylmaleimide (NEM) inhibited cotransport and also blocked the stimulatory effect of calyculin A if administered before calyculin A. Stimulation by calyculin A and deoxygenation were not additive. Staurosporine (2 microM) inhibited deoxygenated-stimulated K+ influxes, but not those stimulated by calyculin A. NEM added during calyculin A stimulation, i.e. during the 5 min lag, caused transport activity to be clamped at levels intermediate between maximal (calyculin A alone) and control. Cells treated with calyculin A alone or with calyculin A followed by NEM were no longer sensitive to volume, isoproteronol or PO2. 4. The results have characterized the interaction between deoxygenation and other stimuli of NKCC activity. They have also shown that it is possible to manipulate the transporter in a reciprocal way to that shown previously for K+-Cl- cotransport.
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Affiliation(s)
- M C Muzyamba
- Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool L69 3BX, UK
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49
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Campbell EH, Cossins AR, Gibson JS. Oxygen-dependent K+ influxes in Mg2+-clamped equine red blood cells. J Physiol 1999; 515 ( Pt 2):431-7. [PMID: 10050010 PMCID: PMC2269147 DOI: 10.1111/j.1469-7793.1999.431ac.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/1998] [Accepted: 12/07/1998] [Indexed: 11/29/2022] Open
Abstract
1. Cl--dependent K+ (86Rb+) influxes were measured in oxygenated and deoxygenated equine red blood cells, whose free [Mg2+]i had been clamped, to examine the effect on O2 dependency of the K+-Cl- cotransporter. 2. Total [Mg2+]i was 2.55 +/- 0.07 mM (mean +/- s.e.m. , n = 6). Free [Mg2+]i was estimated at 0.45 +/- 0.04 and 0.68 +/- 0. 03 mM (mean +/- s.e.m., n = 4) in oxygenated and deoxygenated red cells, respectively. 3. K+-Cl- cotransport was minimal in deoxygenated cells but substantial in oxygenated ones. Cl--dependent K+ influx, inhibited by calyculin A, consistent with mediation via the K+-Cl- cotransporter, was revealed by depleting deoxygenated cells of Mg2+. 4. Decreasing [Mg2+]i stimulated K+ influx, and increasing [Mg2+]i inhibited it, in both oxygenated and deoxygenated red cells. When free [Mg2+]i was clamped, Cl--dependent K+ influxes were always greater in oxygenated cells than in deoxygenated ones, and changes in free [Mg2+]i of the magnitude occurring during oxygenation-deoxygenation cycles had a minimal effect. Physiological fluctuations in free [Mg2+]i are unlikely to provide the primary link coupling activity of the K+-Cl- cotransporter with O2 tension. 5. Volume and H+ ion sensitivity of K+ influx in Mg2+-clamped red cells were increased in O2 compared with those in deoxygenated cells at the same free [Mg2+]i, by about 6- and 2-fold, respectively, but again these features were not responsible for the higher fluxes in oxygenated cells. 6. Regulation of the K+-Cl- cotransporter by O2 is very similar in equine, sheep and in normal human (HbA) red cells, but altered in human sickle cells. Present results imply that, as in sheep red cells, O2 dependence of K+-Cl- cotransport in equine red cells is not mediated via changes in free [Mg2+]i and that cotransport in Mg2+-clamped red cells is still stimulated by O2. This behaviour is contrary to that reported for human sickle (HbS) cells.
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Affiliation(s)
- E H Campbell
- Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool L69 3BX, UK
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50
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Abstract
Ouabain- and bumetanide-resistant K+ influx, and haemoglobin (Hb) O2 saturation, were measured in HbA red cells over a range of oxygen tensions (PO2 values) in the presence and absence of 12C79 (5 mM), a substituted benzaldehyde which increases the O2 affinity of Hb. PO2 values for half-maximal O2 saturation declined from 29+/-2 mmHg (mean +/-SEM, n=3) in control cells to 7+/-1 mmHg with 12C79. In control cells, Cl--dependent K+ influx (indicative of KCl cotransport activity) was fully O2 dependent, i.e. inactive at low PO2 values. By contrast, in the presence of 12C79, KCl cotransport was largely resistant to inactivation at low PO2 values. Substantial cotransport activity was still present (>60% of that at high PO2 values) in N2, although O2 saturation was low (about 10%). In all cases, Cl--independent K+ influxes were low [<0.25 mmol (l cells h)-1] and unaffected by PO2 or 12C79. The significance of these results is discussed.
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Affiliation(s)
- J S Gibson
- Department of Veterinary Preclinical Sciences, University of Liverpool, Liverpool, L69 3BX, UK.
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